On the U-M Gateway: long-held assumption about emergence of new species questioned

By EEB
Sep 04, 2013

Photo of two cinnamon-chested bee-eaters superimposed on an evolutionary tree showing two-thirds of known bird species. Rabosky and Matute used the tree to test whether the ability of bird species to interbreed with other species is related to the rate at which they formed new species. Image credit: Tree illustration and bird photo by Daniel Rabosky.

Darwin referred to the origin of species as "that mystery of mysteries," and even today, more than 150 years later, evolutionary biologists cannot fully explain how new animals and plants arise.

For decades, nearly all research in the field has been based on the assumption that the main cause of the emergence of new species, a process called speciation, is the formation of barriers to reproduction between populations.

But Professor Daniel Rabosky and a colleague are questioning the long-held assumption that genetic reproductive barriers, also known as reproductive isolation, are a driving force behind speciation. Their study was published online publication in the Proceedings of the National Academy of Sciences on Sept. 2, 2013.

"Most research on the formation of species has assumed that these types of reproductive barriers are a major cause of speciation. But our results provide no support for this, and our study is actually the first direct test of how these barriers affect the rate at which species form," said Rabosky, assistant professor in the U-M Department of Ecology and Evolutionary Biology and a curator of herpetology at the Museum of Zoology.